The proposed research will attempt to demonstrate that organo-cobalt complexes, relevant to the B12 coenzymes, undergo equational ligand proton dissociation in aqueous base to form activated complexes with considerable carbanion-like character on the carbon bound to cobalt. A conclusive demonstration will be made that such activated organocobalt complexes undergo attack by relatively weak electrophiles including water and disulfides. This work will provide a model system for enzymatically mediated cobalt-to-sulfur methyl group transfer known to occur in methionine synthesis in humans and methane synthesis in certain microorganisms. The principal objectives include 1) a conclusive demonstration of base-catalyzed electrophilic cleavage of organocobalt complexes by water (to form alkanes) and by disulfides (to form alkyl sulfides) and 2) kinetic studies to determine the sensitivity of these reactions to the electrophilicity of the attacking reagent and the nature of the organocobalt complex. Organo cobalamins and organocobinamides will be used in this work as well as organocobaloximes. The major techniques include UV-vis and proton nmr spectroscopy, gas chromatography, mass spectrometry and manometric techniques.